Refining of lubricating oils



Jan.-25, l944 A R. G LARsl-:N Erm.' 2,339,785Y

REFINING OF LUBRICATING OILS Fig. I

lnvzniors: Rober* 6. Larsen ForrzsfJW *son 5L, #wir AmmeqnLL/ fi Jul.- 25, 1944 R. G. LARsEN Erm.

REFINING 0F LUBRICATING OILS 2 Sheets-Sheet 2 Filed Nav. 30, 1942 mm Pio: Je: Q m 4 N. w .m l A. w F

?atented Jan. 25, 1944 unirsey s'rnres PATENT REFINING OF LUBRICATING OIL Robert G. Larsen, Albany, and Forrest J. Watson, Oakland, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of vDelaware I Application November 30, 1942, Serial No. 467,462

(ci. 19e-13) 16 Claims.

the oil with a small amount of aluminumchloride at elevated temperature of incipient cracking,

but probably below temperatures at which cracking predominates. During this treatment the aluminum chloride forms complexes with the undesirable impurities in the lubricating oils, some of which complexes form a sticky sludge which can be removed by settling, while other` complexes are oil-soluble and must be removed by washing and/or clay treatment. The aluminum chloride complex precipitates generally are not very dense compounds as compared to the-density of the oil, and therefore are usually very slow to settle and hard to separate from the oil. Also, since aluminum chloride is such a strong reactive chemical some undesirable cracking of the oils treated usually occurs.

Liquid antimony trichloride treatment of hy.

drocarbon oils is a selective solvent treatment and extracts the impurities from the oils. The liquid antimony trichloride has the advantage over aluminum chloride for treating lubricating oils inP that the former is much denser and settles from the oils much more readily. Since antimony trichloride melts at 73 C. it can be readily4 used as a liquid -and thus insures much more intimate contact with the impurities in the oil` ils-usually severaltimes the volume of the oil treated-are required to obtain the same degree of refinement as with aluminum chloride.

The process of this invention combines the advantages of both antimony trichloride-solvent r extraction and aluminum chloride-chemical treatment, producing a iinai product more highly rened than either treatment separately could produce, as well as minimizing the disadvantages of each treatment. The'advantages of such a combined treatment include: increasing the se lectivity for aromatics and sulfur in the hydrocarbon oils; increasing the chemical activity of aluminum chloride; increasing the dispersion of aluminum chloride through the oil; increasing the removal and speeding the separation of the aluminum chloride sludge from the oil; reducing the amount of antimony trichloride necessary for the treatment over use of antimony trichloride alone and thereby also reducing the amount of v antimony trichloride to be recovered;` and reducing the high temperatures required to obtain active treatment as compared with thaty of aluminum chloride alone and thereby minimizing cracking.

Some'of the purposes of the process vof this invention are to remove economically and quick- 1y aromatics, unsaturates, oxygen, sulfur, nitrogen organic compounds, etc., from hydrocarbon oils; to improve oxidation inhibitor susceptibility in hydrocarbon oils as measured by the induction period; to improve the color of hydrocarbon oils; toeliminate constituents which are responsible for the formation of insoluble sludge on oxidation of the hydrocarbon oils; to reduce the sludging tendency of hydrocarbon lubricating oils; to remove mercaptans from gasoline and lighter hydrocarbon oils; to facilitate the sludge separation from hydrocarbon oils treated: to reduce decomposition of hydrocarbons contacted v,with aluminum chloride; and many others, which will appear from time 'to time in the description which follows. In summary, a primary purpose of this invention is to combine the advantages of antimony trichloridesolvent extraction and alumi inatesfrom solvent extraction of oils rich in parailinic hydrocarbons;l oils having received various pretreatments such as sulfuric acid treatment; fatty' oils; fatty acids; etc. However, hydrocarbon oils of the lubricating oil range which are highly paraiiinic, e. g., solvent extracted oils, are most responsive to the treatmentv of this invention, and niore'particularly antimony trichloride extracted oils in which the process of this invention is a iinishing treatment.

Preferably the process of this invention may be divided into nine major steps, sevenof which are essential to the eillcient operation of the process, and the last two of which are additional preferred steps to produce a purer iinlshed product. These steps are: l l y y (l) The contact step, which comprises con-I meting the hydrocarbon ou to be treated with a slurry of aluminum chloride dispersed in liquid antimony trichloride. ywhich slurry reacts with and extracts the impurities present in the hydrocarbon oil to produce a mixture of slurry and oil.

(2 The separation step, which comprises the separation of ,said slurry and oil mixture into a rafnate or upper phase containing a small portion of the antimony trichloride, and an extract or lower phase comprising unused aluminum chloride and its sludge including complexes, ex-

' tracted oils, and the remaining major portion of the antimony trichloride. l

(3) The raiilnate recovery step, which comprises removal of the antimony trichloride from the rafllnate phase by blowing it with a heated inert carrier gas'at a reduced pressure to vaporize the antimony trichloride from the raiiinate oil and produce aliquid raiilnate oil free of antimony trichloride, and a vapor consisting of the antimony trichloride, said inert lcarrier gas and a small amount of hydrocarbons, which latter accumulate in the antimony trichloride due to unavoidable cracking of the oil being treated in this and the previous steps.

(4) The extract recovery step, which comprises the removal of antimony trichloride from the extract phase by the same method as used in step3 to produce an extract free from antimony trichloride, and a vapor containing the antimony trichloride, inert carriergas, land a small amount of accumulated hydrocarbons.

(5) The antimony trichloride separation step, which comprises the separation of the antimony trichloride from the vapors produced in steps 3 and 4 by condensation of at least a portion of the accumulated liqueilable hydrocarbons and the antimony trichloride from said vapors.

(6) 'I'he antimony trichloride purification powdered aluminum chloride is fed by a screw conveyor or other suitable means (not shown) and the aluminum chloride powder added may vary from about 5 to 15% by weight of said oil; preferably about 10% by weight of each antimony trichloride an'd aluminum chloride are used. Accordingly, the percentage of slurry to the oil to be treated may vary from about 10 to 215% by weight.

Inert diluents such as pentanes, hexanes, octanes, alcohols, ethers, naphthas, and gasolines may be employed with the oil and be introduced through valved line I5 to decrease the viscosity of the oil and thereby` decrease the settling time of the sludge formed during the treatment. If diluents are used they must be subsequently removed from the oil by an additional step not disclosed in this process, such as by fractionally distilling the raiiinate oil. Suitable quantities of diluents may vary anywhere from a fraction to Y several volumes of the oil.

step, which comprises the removal of the accumui lated liquid hydrocarbons in that portion ofthe vapors condensed in step 5.

('l) 'I'he antimony trichloride recovery step. which comprises the removal of the antimony trichloride from the remaining uncondensed p0rtion of the vapors from step 5 by reabsorption of the antimony trichloride therein in the oil feed entering step 1.

The mixer I0 is heated to above labout. '73 C., the melting point of pure antimony trichloride,

and preferably to between about '70 and 150 C.

It is very important to keep both oxygen and water out of the system at all times in this step as well as the steps to follow, except step 9; and accordingly an atmospheric pressure blanket of an inert gas such as methane, ethane, natural gas, hydrogen, nitrogen, etc., is employed whenever possible. g

The mixing is -continued from lo'minutes to about 2 hours, depending upon the oil treated, the temperature employed, the amount of aluminum chloride and antimony trichloride employed, and the degree of treatment desired. Usually, however, the treatment is for about a period of one hour. After the treatment has been com- 46 pleted the oil slurry mixture is withdrawn from (8) The raffinate purification step, which comprises clay treatment oi the ramnate free of an timony trichloride produced in step r3.

(9) The extract purification step, which coml prises stripping the aluminum chloride from the extract which has been freed from antimony trichloride in step 4 by steam-stripping and hy- AIii) drolyzing the aluminum chloride andits complexes to produce two layers, an oily extract -or upper layer; and an aqueous or lower layer; and separating said layers. u Figure I of the accompanying drawings shows a flow diagram oi' invention.

Figure II is a graph comparing the inhibitor susceptibility of an oil treated by this process with that of other treatedoils. v

'Ihe following description is a detailed explanation'of the 'F diagram disclosed in Figure I of the drawings which, for purposes of illustration, has been adapted as a ilnis'hing treatment fora solvent-treated lubricating oil. 1) Contact sten-Referring to the drawings, oil to be treated is introduced into the closed and steam jacketed mixing kettle III through valved oil feed lineI I. 'I'he mixer I0 is agitated y by stirrer I2. Liquid antimony trichloride slurry 'containing suspended aluminum chloride powder a preferred embodiment of this kettle I0 through valved line I6 and another batch is prepared inl the kettle.

(2) The separation step-From kettle III in step 1 above, the mixture of oil and slurry passes through line I 8 to settler 20, which is of suiilcient capacity to act not only as a liquid phase sep.

arator but also as a surgey tank so that the remaining steps of the process may be carried out continuously. In settler 20 the mixture separates into an upper or raillnate oil phase and a lower or extract-sludge phase. Both phases contain liquid antimony trichloride, the major portion of antimony trichloride, however, being in the extract phase. The extract -phase also contains aluminumchloridesludge and its oil complexes, as well as aromatica' and unsaturates and some naphthenic oils extracted from the hydrocarbon oil feed by the antimony trichloride. The ramnate oil layer is continuously withdrawn from settler 20 through swing pipe 2I and valved line 22 in the side of settler 20, and the extract sludge phase is withdrawn through valved line 23 at the bottom of settler 20.

The temperature oi' the mixture is maintained at all time's above about 73 (2.-, (the melting point of antimony trichloride) so that both phases will remain substantially in the liquid state.

A centrifuge or otherlmechanical apparatus may be employed in this step to aid the separavtion of the two phases.

assenso Also, a countercurrent liquid extractor column may be used to combine steps 1 and 2 above described,` if desired, and the cils treated permit the use of such apparatus.

(3) .The raznatc recovery sten-From settler `2Il the raiinate phase is passed through valved line 22 and through a' heater 3l into railinate stripper 30 wherein the antimony trichloride isv (not shown) may be employed to maintain thetemperature in stripper 30 Within the vproper limits of 110 to 150 C. The reduced pressure in stripper 30 and other pieces of apparatus in the process through step 7 is provided by an exhauster 11, which will be described later and maintains a subatmospheric pressure in this and the intervening steps of between about and 100 mm. of mercury.

The vapors of inert gas and antimony trichloride, together with a small amount of accumulated hydrocarbons, pass from the top of stripper through line 33 and raiiinate free from antimony trichloride is withdrawn from the bottom of stripper 30 through line A36 into surge tank 35.

From tank the ramnate oil may be withdrawn as a iinal product through valved line 36, or it may be further purified as described in step 8.

(4) Etractrecooery step-From settler 20 the extract-sludge phase is passed through valved line 23 and heater 6I into extract stripper d6 maintained at a reduced pressure similar to strip-1 per 30, but usually maintained at a temperature about 25 C. below that of stripper 30 because of the aromatics and impurities present in the extract phase, which more readily react at the higher temperatures with the antimony trichloride and aluminum chloride present. Inert carrier gas is preheated in heater 42 and is introduced near the bottom of stripper 66. Because of the larger amount of antimony trichloride present in the extract sludge and the lower temperature employed in stripper 30, it is necessary usually to introduce a larger volume of inert gas in stripper 40 than in stripper 30. Side heaters (not shown) may also be employed on stripper 40 to maintain the temperature not over about 125 C. and not below about 110 C.

'I'he vapors of inert gas andantimony trichloride, together with a small amount of accumulated hydrocarbons, pass out the top of stripper 40 through line 43 and join line 33 of the vapors from stripper 30; and the extract sludge now containing unused aluminum chloride and itscomplexes, but free of antimony trichloride, is withdrawn from the bottom of stripper 46 through valved line Il and may be discarded or the extract may be purified as described later in step 9.

(5) Antmony trichloride separation step.- The vapors of antimony trichloride and gas in lines 33 and 43 (from strippers 3U and 40 re-4 spectively) are joined and enter condenser 56, wherein they are cooled to a temperature just above the melting point of antimony trichloride at the maintained reduced pressure. These vapors are then passed into accumulator 5l. wherevent in line 65.

in the condensed antimony trichloride and accumulated liquidhydrocarbons are removed. If

the amount of liquid hydrocarbons accumulated in the antimony trichloride is not so great as to cause objectionable dilution ofthe antimony trichloride, the purication step may be partly or Wholly bypassed through valved line 54 to join line I3 and the antimony trichloride `may be returned to kettle I il wherein fresh aluminum chloride is admitted from line I6 as described above. If make-up antimony trichloride must be added it may be introduced into valved line I3 through valved line 55.

(6) The antiffzony trichloride purification sten-Usually it is necessary to purify at least a portion if not all of the condensed vapors from accumulator 5I each cycle. Accordingly, they are passed through valved line 63 into extractor 60 wherein the liquid hydrocarbons, which have accumulated in the antimony trichloride due to unavoidable cracking 'of the oils treated in the previous steps of this process, are extracted by a suitable stable 'low boiling liquid hydrocarbon solvent which enters the bottom of extractor 60 from condenser '6L The hydrocarbon solvent must be inert to antimony trichloride at the temperatures involved, boil below the boiling temperature of the liquid accumulated hydrocarbons and antimony trichloride, and be more miscible with the liquid hydrocarbons therein than antimony trichloride. Such a solvent may be paraiiinic hydrocarbons such as butanes, pentanes, hexanes, etc., n-butane and n-pentane being preferred. 1 The liquid hydrocarbons, which are miscible in the solvent, form a separate upper pihase which is withdrawn from the top of extractor 60 through line 62 to stripper 64 wherein the hydrocarbon solvent is vaporized from the extracted liquid hydrocarbons and returned from the top of stripper 64 through line 65 to condenser 6l and extractor 66, and the remaining liquid hydrocarbons are-withdrawn from the bottom of stripper 64 through valved line 66 and may be discarded, burned or used as a blending stoc for stove oils or other fuels, as desired. l

The antimony trichloride substantially free from the liquid hydrocarbons is withdrawn from. the bottom of extractor 60 together with some hydrocarbon solvent through line 6l toanother stripper 63 wherein the hydrocarbon solvent, which is selected to be more volatile than the aitimony trichloride, is distilled from thev antimony trichloride to join the hydrocarbon sol- The puried antimony trichloride substantially .free from all hydrocarbons is withdrawn from the bottom of stripper 38 through line 69, which joins line I3 returning the antimony trichloride to kettle I Il as described above. The strippers 66 and 68 are provided with reboilers at their bottoms to vaporize the hydrocarbon solvent from the liquids therein and may also be providedwith -reux at their tops (not shown) to obtain better fractionation.

(7) The antimony trichloride recovery step.- The uncondensed vapors in accumulator 5I which are passed from the top of accumulator 5I through line 52 enter the absorber 10, Wherein they are contacted with at least a portion of the untreated oil from the feed line II, introduced near the top of absorber 'I0 through valved line 1I. This line 1I may be provided, if desired, with a heater 'I2 to ,decrease the viscosity of the oil and increase its eiiiciency and utility in absorbing and removing theremaining portion of the antimony trichloride inthe vapors.

The oil feed containing small amounts of antimony trichloride and possibly some nonliquefiable accumulated hydrocarbons is withdrawn from the bottom of the absorber through line 13 into the surge tank 1I from which it is withdrawn through valved line 15 into feed line and mixer I0 as desired. Inasmuch as this feed already contains some antimony trichloride, the amount of antimony trichloride admitted to this mixer through line I3 would be the difference between the amount required in the treatment and that contained in the feed oil.

The residual gas free from antimony trichloride now consisting of the remaining accumulated hydrocarbons and the inert carrier gas, obtained in absorber 10, returns through valved line 16 containing exhauster 11 to strippers 30 and`40. Excess gas from exhauster 11, if any, or gas that is fouled, may be withdrawn through valved line 18 and discarded or used as a fuel. Make-up gas may be introduced into the system through valved line 19.

The' 'exhauster 11 maintains a subatmospheric pressure of between about 20 and 100 mm. of mercury on the absorber 1|),` accumulator 5|, condenser 50, strippers and` 40, and the linesV connecting them as previously mentioned. The advantage of placing one large exhauster here rather than one. small exhauster on each of the above mentioned units avoids corrosion which would take place'in several of the smaller exhausters from antimony trichloride vapors produced in these units, whereas the gas at the top of absorber 10 is free from antimony trichloride. The carrier gas employed in the described process must be inert toward both antimony trichloride and the oilfeed at the temperatures employed, and must'also be free of water vapor and oxygen. Some gases which may be used include: the saturated hydrocarbon gases boiling below 10 C., such as methane, ethane, propanes, lbutanes; natural gas; dimethyl ether; nitrogen; or the like.

i 8) Ranate purification step-The raillnate collected in surge tank may be' further treated and purified, ifdesired, by introducing a batch of it into a heated agitator or clay treater 8|) through valved line 8| and mixing with it some adsorbent or lubricating oil treating clay, such as Florida clay, Attapulgas clay, acid-activated clay, bentonite, or the like, from valved line 82.

out cracked lighter hydrocarbons and impurities, separates the extracted oils, and hydrolyzes the aluminum chloride, thereby producing respectively a vapor which is withdrawn through vent' line 93 in the top of hydrolyzer 90, an upper oily layer of extract which is withdrawn through the side valved line 94, and a lower layer comprising water-soluble products of hydrolysis, tars, etc-.,.

which latter layer is withdrawn and discarded through valved line 95 at the bottom of hydrolyzer 90. The hydrolyzer may be provided with a water condenser (not shown) near its top to condense steam necessary for the formation of the aqueous layer.

The extract oil comprises aromatics. naphthenes. and/or sulfur, oxygen and/or nitrogen organic compounds, which are detrimental and undesirable in the oil treated. The vapors from' the vent line 93v may be discarded or used as a fuel. y

Incidental parts of the apparatus, such as additional heaters, valves, tanks, pumps and the art.

like, are not shown, and their placement is Within the common knowledge of those skilled in the The process may be run continuously, -intermittently and/or batchwise, as desired. l

The following comparative examples show the advantage of the combination shoe-A1013 renn- After completed contact in agitator 80 to remove remaining traces of impurities, the clay oil mixture is withdrawn from the bottom of kettle through valved line 83 and passed through filter 84 to remove the clay. The resulting refined oil is withdrawn from the filter 84 through line 85 as the final purified product.

Instead of "contact treatment with line clay, percolation through a filter bed maybe used. Sometimes clay treatment may be dispensed with, in which case the nished oil is withdrawn from tank 35 through valved line 36 as. mentioned above.

(9) The extract recovery sten-If the extract sludge containing mostly aluminum chloride and its oil complexes from the extract stripper l0 isnot discarded through valved line 44 it maybe passed into the hydrolyzer 90, through valved line 9|, and therein contacted with live steam (some of which is allowed to condense) entering near the bottom of the hydrolyzer through valved line 92. '.Ihis steam agitates the sludge, strips ing over treatments employing approximately equal amounts of either SbCla or AlC'la alone at 80 C.`on the same oil, namely a Mt. Poso, California, lubricating oil extracted with furfural to 50 V. I. Each of these examples was treated under the same conditions including a finishing clay treatment.

Pei-cent 0n finished oil we|ght treating agent Specific sulfur dispersion i The inhibitor susoeptibuities of tneabove ous were then determined by adding .1% phenyl al-A pha naphthylamine to a portion.of each and subjecting inhibited as well as uninhibited samplesto an oxygen absorption test in the presence of metallic copper. Results of these tests are shown in Figure II of the drawings, wherein the amount of i, oxygen absorbed. is plotted against time. Six curves are shown corresponding to the following samples and having approximately the following induction periods.

A proximate ducizgiin lilielours y wt. of Sample inhibitor Curves The last column of this table shows another advantage of the combination lSbCila-AlCli treatment of this invention, viz., the lower percent of isopentane insolubles present in the finished oil after the oxidation test which is a measure of the sludging tendency of the oil.

essaies antimony trichloride with fresh aluminum chics ride for further contact with more hydrocarbon oil. c

9. A continuous process for refining hydrocar-1 bon oil comprising the steps of: contacting said. oil with a slurry of aluminum chloride dispersed in liquid antimony trichloride at a temperature above about '73 C., winch slurry consists essentially of equal portions of aluminum chloride and 2. The process of claim 1 wherein the hydrocarbon oil is a mineral lubricating oil rich in parainic hydrocarbons.

3. The process of claim l. wherein the amount oraluminum chloride and antimony trichloride is about oi each by weight.

d. A process for treating a hydrocarbon oil comprising contacting said oil with a slurry of aluminum chloride dispersed in liquid-antimony trichloride to, produce two phases, each of which` contains antimony trichloride, separating said phases. and separately removing the antimony trichloride from each phase.

5. A process for rening a hydrocarbon oil comprising contacting said oil with a slurry of aluminum chloride dispersed in liquid antimonif trichloride to produce a ramnate phase and an extract sludge phase, each of which contains antimony trichloride; separating said phases and separately vaporizing the antimony trichloride from the rafhnate phase and from the extract sludge phase to produce a rate oil, analuminum chloride sludge` containing extract oil, and vapors oi antimony trichloride; condensing at least a portion of the antimony trichloride vapore; and recycling said condensed antlmony trichloride for further contact with more hydrocarhon oil.

-6. A continuous process for treating hydrocarbon oil comprising contacting said oil with a slurry of aluminum chloride dispersed in liquid lantimony trichloride to produce a raiiinate phase and an extract sludge phase, each of which contaihs antimony trichloride; separating said phases; separately vaporizing the antimony trichloride from the rainate phase and from the extract sludge phase with an inert carrier gas to produce a raiiinate oil, an aluminum chloride sludge containing extract oil, and vapors conantimony dichloride; separating the an.- 'timony trichloride from said vapors; and recycling said separated antimony trichloride from further contact with more hydrocarbon oil.

'1. The process of claim 6 wherein the inert carrier gas is natural gas.

8. A continuous process for rening hydrocarbon oil comprising contacting said oil with a slurry of aluminum chloride dispersed in antimony trichloride to produce a railinate phase and an extract sludge phase, each of which contains antimony trichloride; separating said phases; separately vaporizing the antimony trichloride from the ramnate phase and from the extract Y sludge phase with an inert carrier lgas to produce a railnate oil, an aluminum chloride sludge containing extract oil, and vapors containing antimany trichloride, liqueable hydrocarbons produced from cracking of the oil treated and said inert carrier gas; condensing at least a portion o! the antimony trichloride and liqueable hydrocarbons Irom said vapors; separating at least a portion of the liquid hydrocarbons from said condensed antimony trichloride to produce liquid antimony trichloride substantially free of said liquid hydrocarbons; and mixing Said Separated 75 and trom the extract sludge phase with an inert l antimony trichloride to produce a raihnate phase and an extract sludge phase, each of which contains 'emtimony trichloride; separating said phases; separately vaporizing the antimony trichloride from the raiinate phase at a temperature between about 110 C. and 150 C. and from the extract sludge phase at a temperature not over about 12590., each at a reduced pressure,

with an inert carrier gas to produce a raflinate oil, an aluminum chloride sludge containing extract oil, and vapors containing antimony trichloride, liqueflable hydrocarbons produced from cracking of oil treated in lprevious steps and said inert carrier gas; condensing at least a portion of said antimony trichloride and liqueabie hydrocarbons from said vapors; purifying at least a portion of said condensed antniony trichloride by removing the liquid hydrocarbons therefrom with normal pentane to produce liquid antimony trichloride substantially free of inert carrier gas and liquid hydrocarbons; and recycling saidpurified antimony trichloride for further contact with is contacted with said hydrocarbon oil at a temperature between about 70 C. and 150 C.

1l. The process of claim 9 wherein the antimony trichloride is vaporized from said phases at a subatmospheric pressure between about 20 and mm. of mercury. l

12. The process of claim 9 plus the additional step of clay-treating said raiiinate oil.

13. The process of claim 9 plus the additional steps or hydrolyzing said aluminum chloride sludge containing extract oil to produce an extract oil layer, and an aluminum chloride layer, and separating said layers.

14. A continuous iinishing process for refining eral lubricating oil rich in parai'nic hydrocarbons comprising the steps or: extracting said oil with antimony trichloride; contacting said oil with a slurry of equal portions of aluminum chloride and antimony trichloride at a temperature above about 73 C, to produce a ramnate phase and an extract sludge phase, eachiof which contains antimony trichloride; separating said phases; separately vaporizing the antimony trichloride from the ramnate phase and from the extract sludge phase at a subatmospheric pres-l a ramnate phase and an extract sludge phase,

each of which contains vantimony trichloride; sepmatins said phases; separately vaporizing the antimony trichloride from the rafinate phase carrier gas to produce a raiilnate oil, an aluminum chloride sludge containing extract oil, and vapors containing antimony trichloride, liqueilable hydrocarbons produced from cracking of oil treated in previous steps and said inert carrier gas;'condensing at least a .portion of the antimony trichloride and liqueable hydrocarbons from said vapors; extra'ctively distilling at least a portion of said condensed antimony trichloride and liquid hydrocarbons with normal pentane to produce liquid antimony trichloride substantially free of said liquid hydrocarbons; separating the antimony trichloride from the remaining uncondensed vapors with at least a portion of said il to be treated to produce an inert carrier gasl substantially free of antimony trichloride and a hydrocarbon oil containing antimony trichloride for contact with said slurry; recycling said inert carrier gas to said raffinate phase and said extract sludge phase; mixing said condensed antimony trichloride with fresh aluminum chloride for further contact with more hydrocarbon oil; claytreating said ralnate oil; and steaming said aluminum chloride sludge containing extract oil to produce an extract oil layer and an aqueous aluminum chloride layer and separating said layers.

16. A continuous iinishing process for treating solvent e'xtracted mineral lubricating hydrocaribon oil comprising vthe stepsof: contacting said oil with between about 10% and 215% by weight on the oil of a slurry of aluminum chloride dispersed in liquid antimony trichloride at a tem-v perature between about 70 C. and 150 C. to

produce a ranlnate phase and an extract sludge phase, each o1 which contains antimony trichloride; separating said phases; separately Vaporizing the antimony trichloride from the raffinate phase at a temperature between about C.

and 150 C. and from the extract sludge phase at a temperature not over about C., each at a pressure between about 20 and 100 mm'. of mercury, withnatural gas to produce a railinate oil, an aluminum chloride sludge containing extract oil, and vapors containing antimony trichloride,

Vliquefiable hydrocarbons produced from cracking of oil treated in previous steps, and said natural gas; condensing at least a portion of the antimony trichloride and liquefiable hydrocarbons" from said natural gas; purifying at least a portion of said condensed antimony trichloride and liquid hydrocarbons with normal pentane to pro-A duce liquid antimony ytrichloride substantially 'free of liquid hydrocarbons; extracting the antimony trichloride from' the remaining uncondensed vapors with at least a. portion of said oil to be treated at a reduced pressure of between about 20 and 100 mm. of mercury to produce an inert carrier gas substantially freeof antimony trichloride for recontact with said raffinate phase and said extract sludge phase, and a hydrocarbon oil containing antimony trichloride for contact with said slurry; and recycling said purified liquid antimony trichloride for further contact with Imore hydrocarbon oil.

ROBERT G. LARSEN. FORREST J WATSON'. 

